Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Patent
1999-09-27
2000-12-05
Hoang, Tu Ba
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
373 78, 373 80, F27D 300
Patent
active
061576654
DESCRIPTION:
BRIEF SUMMARY
FIELD OF APPLICATION
This invention concerns a system to load scrap by means of baskets for an electric arc furnace, and also the relative system.
The invention is applied in the field of steel production in order to load, by means of baskets, the electric furnaces with scrap which is pre-heated by means of the fumes coming from the said electric furnaces.
The electric arc furnaces to which the invention is applied can be of the type fed by alternating or direct current.
The invention makes it possible to reduce the times needed to open the roof of the furnace in order to load the furnace, thus limiting the heat losses from inside the furnace.
Furthermore, the invention makes it possible to load the furnace with scrap which has been heated in the same moving basket used to unload the scrap into the furnace. Moreover, the invention makes it possible to simplify and automate all the movements needed for loading, to reduce the times of the cycle, and minimises the spaces required and the equipment employed.
STATE OF THE ART
The state of the art includes electric arc furnaces used to produce steel from scrap and regenerated material of various types.
In the state of the art, the furnaces can be loaded continuously, for example by means of conveying means such as a belt, connected with the inside of the furnace and fed continuously with fresh scrap which gradually replaces that already loaded into the furnace.
In another solution, the furnaces are loaded discontinuously by means of baskets or containers. The baskets, in one or more successive steps, are loaded in a scrap-loading zone and then transported, by lifting and moving means, in correspondence with the mouth of the furnace which is kept open.
The bottom of the basket is then opened and the material is unloaded inside the furnace. For this purpose the baskets are equipped at the bottom with movable doors, valves, teeth, sliding grates or other appropriate opening system.
Systems using baskets for loading the furnace which are known to the state of the art have a plurality of disadvantages.
Firstly, it takes a long time to open the furnace which causes a considerable heat loss from inside the furnace towards the outside, and also the leakage into the surrounding environment of fumes containing powders, incandescent particles and other pollutants.
A further disadvantage is that if the scrap is loaded cold into the furnace, it takes longer to melt and causes problems for the penetration of the electrodes.
At present, in some steel plants the furnaces are loaded with scrap which is pre-heated by the heat of the fumes discharged from the furnace itself through the fourth hole on the roof.
WO 92/10594 discloses a method and a facility for producing steel by melting scraps, wherein the scrap is preheated in a basket by the fumes coming out from an electric arc furnace having a lowed shell ad a roof. The fumes leave the furnace through the roof and are conducted by ducts to a combustion chamber before being introduced in the basket through the removable roof thereof. The basket is placed in a removable manner on a moving mechanism for being translated or rotated from a first preheating position to a second unloading position. The roof of the furnace con be rotated by a second moving mechanism from a closed position to an open position.
The facility described in this document has the disadvantage that the roof of the furnace must be completely open before the basket containing the scrap is moved in its unloading position. This causes that the furnace remains open for a long period of time, so causing a big quantity of fumes to leave the furnace and diffuse into the surrounding environment, with a considerable pollution and heat loss.
Loading systems known to the state of the art where the scrap is pre-heated use loading baskets located in the appropriate rooms into which the fumes are conveyed before they are purified and discharged by the appropriate plants.
There are also solutions known to the state of the art which include a single room which contains sev
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Benedetti Giampietro
Della Negra Angelico
Gensini Gianni
Pavlicevic Milorad
Poloni Alfredo
Danieli & C. Officine Meccaniche SpA
Hoang Tu Ba
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